Recently, a high frequency hyperthermal method has been developed where a cancerous tumor is destroyed by heating the affected part utilizing the fact that cancer cells are weaker against heat than normal cells.
In a high frequency hyperthermal method disclosed in a prior art example, such as Japanese Patent Laid Open No. 135067/1984, a conductive material such as a metal needle is arranged in the position of an object to be heated (cured) as an affected part in a living body. The position to be heated is held with a pair of opposed electrodes and a high frequency current is mad.RTM.to flow between both electrodes to concentrate the electric field at the metal needle and locally heat the part near the metal needle
The above mentioned prior art example requires surgical treatment to set and remove the metal needle, thereby increasing the burden on the patient and has not often been practical in case the patient is in a weakened state.
One defect with the above mentioned hyperthermal method, is when it is used in a biliary duct closure. The internal pressure within the biliary duct will rise before the therapeutic effect is obtained and, unless the liquid is drained, death can occur
Japanese Utility Model Laid Open No. 69716/1984 discloses a hollow tubular heater for curing cancers. One defect with this prior art example is that it requires lead wires ;or heating. Therefore, the heater gives the patient an unpleasant feeling and, during meal time, the lead wires will be in the way.
On the other hand, When a narrowed part is made in the end part of a biliary duct, a hollow tubular detainable tube is detained to prevent the biliary duct from being closed as disclosed, for example, in Japanese Utility Model Laid Open No. 180442/1985.
As shown in FIG. 1, in the detainable tube 111, a tube body 113, having an inner cavity 112, is tapered on one end to form an opened tip part 114. The tube body 113 is provided with escape preventing flaps 115 near the tip part 114 and 116 on the other end.
However, when the cause of making a narrowed part in a biliary duct is due to a cancerous tumor, the above mentioned conventional detainable tube 111 will not be able to fundamentally cure the closure.
Also, USP 4,587,978 discloses a means of heating a body depth from outside the body but does not disclose a means to be detained within the body or a method of coping with the disease that closes the biliary duct.